• APS-C 355.7mm2
  • 14.2 megapixels
  • ISO 100 - 3200
  • APS-C 361.2mm2
  • 25.7 megapixels
  • ISO 100 - 1,600,000

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Differences

Nikon D3100 advantages over Pentax K-3 III

  • Bigger pixels
    ~ 5.01 vs 3.76 microns
    Better low-light and dynamic range (all else equal)
  • Internal flash
    Internal flash vs None
    Useful in a pinch for fill flash
  • Bigger JPEG buffer
    100 vs 30 shots
    Take more JPEG shots before waiting (burst mode)

Pentax K-3 III advantages over Nikon D3100

  • Focus peaking
    Peaker vs Non-peaker
    Your camera will highlight what's in focus
  • In-Camera Image Stabilization
    Yes vs No
    Reduces the effects of camera shake at slower shutter speeds
  • Shoot 4K video
    4K (UHD) vs 1080p
    Make sure you have a fast computer
  • Touchscreen
    Touch vs No touch
    Interact with your camera just like your smartphone
  • High resolution composite
    Yes vs No
    Combine multiple shots to form a super hi-res version
  • Built-in Wi-Fi
    Wi-Fi vs None
    Share your photos wirelessly
  • Built-in Bluetooth
    Yes vs No
    Always-on wireless connectivity
  • Longer stills battery life
    More info 800 vs 550 shots
    Capture more photos
  • Top deck display
    Yes vs No
    Check settings with a screen on top of the camera
  • External Mic Jack
    Jack vs No jack
    Improved sound fidelity when shooting video
  • More cross-type AF points
    25 vs 1
    Cross-type AF points improve autofocus performance
  • Pentaprism viewfinder
    Pentaprism vs Pentamirror
    Much better viewfinder picture fidelity
  • Newer
    4 years vs 14 years old
    Newer cameras often support more advanced features
  • More dots on screen
    1620k vs 230k dots
    Can mean greater resolution or a brighter screen
  • More viewfinder magnification
    1.05x vs 0.53x
    Get a bigger view of the scene through the eye-level viewfinder
  • More pixels
    25.7 vs 14.2 megapixels
    Higher resolution photos
  • Shoots 60p video
    Yes vs No
    A faster framerate can give you more editing options
  • Dual card slots
    Yes vs No
    Gives you more storage flexibility
  • More AF points
    101 vs 11
    More AF points improve autofocus
  • Headphone jack
    Yes vs No
    Monitor audio recording while you shoot video
  • Optional anti-aliasing filter
    Optional vs Fixed
    Lets you choose sharper photos or reduced moiré
  • Faster JPEG shooting
    12.0 fps vs 2.9 fps
    Faster JPEG shooting (burst mode)
  • Faster shutter
    1/8000 vs 1/4000 sec
    Shoot wide open in bright light
  • Higher extended ISO
    1600000 vs 12800 ISO
    Higher extended ISO can give more low-light flexibility

Similarities

Common Strengths

  • Eye-level viewfinder
    Both provide
    You'll be able to frame photos even when the sun is out
  • HDMI out
    Both provide
    Use HDMI output to monitor or review video
  • Hot shoe
    Both provide
    Off-camera flashes open new possibilities
  • Bulb shutter
    Both provide
    Hold the shutter open manually for long exposures

Common Weaknesses

  • Tilt-swivel screen
    Neither provide
    Tilt and swivel the screen for maximum shooting flexibility
  • In-camera panoramas
    Neither provide
    Stitches multiple shots into a panoramic photo
  • Tiltable Screen
    Neither provide
    Tilt the screen for shooting flexbility
  • NFC
    Neither provide
    Simplifies pairing your camera with supported phones
  • Built-in GPS
    Neither provide
    Geotag your photos
  • On-sensor phase detect
    Neither provide
    Usually improves live view and video AF performance
  • Slow-motion videos
    Neither provide
    Shoot slow-motion videos

User reviews

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Buy the Nikon D3100

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Buy the Pentax K-3 III
Body Only
  • Body Only
  • Kit with 20-40mm F2.8-4 Lens
  • Kit with 55-300mm f/4.5-6.3 Lens
All K-3 III Deals

Review Excerpt

The Competition

Compared to Sony DSLR-A380

Nikon D3100
Sony DSLR-A380
  • $700
  • APS-C
  • Lens selection
  • Less expensive
  • $849
  • APS-C
  • In-Camera Image Stabilization
  • Tiltable Screen

Compare Nikon D3100 vs Sony DSLR-A380

Pentax K-3 III
Sony DSLR-A380
  • $1847
  • APS-C
  • Lens selection
  • Focus peaking
  • $849
  • APS-C
  • Bigger pixels
  • Tiltable Screen

Compare Pentax K-3 III vs Sony DSLR-A380

Compared to Sony A33

Nikon D3100
Sony A33
  • $700
  • APS-C
  • Lens selection
  • Fast startup
  • $540
  • APS-C
  • In-Camera Image Stabilization
  • In-camera panoramas

Compare Nikon D3100 vs Sony A33

Pentax K-3 III
Sony A33
  • $1847
  • APS-C
  • Lens selection
  • Focus peaking
  • $540
  • APS-C
  • Bigger pixels
  • In-camera panoramas

Compare Pentax K-3 III vs Sony A33

Compared to Pentax K-r

Nikon D3100
Pentax K-r
  • $700
  • APS-C
  • Less expensive
  • Higher effective ISO
  • $850
  • APS-C
  • In-Camera Image Stabilization
  • Fast startup

Compare Nikon D3100 vs Pentax K-r

Pentax K-3 III
Pentax K-r
  • $1847
  • APS-C
  • Focus peaking
  • Shoot 4K video
  • $850
  • APS-C
  • Bigger pixels
  • Internal flash

Compare Pentax K-3 III vs Pentax K-r

Compared to Pentax KP

Nikon D3100
Pentax KP
  • $700
  • APS-C
  • Bigger pixels
  • Fast startup
  • $999
  • APS-C
  • Focus peaking
  • In-Camera Image Stabilization

Compare Nikon D3100 vs Pentax KP

Pentax K-3 III
Pentax KP
  • $1847
  • APS-C
  • Shoot 4K video
  • Touchscreen
  • $999
  • APS-C
  • Less expensive
  • Tiltable Screen

Compare Pentax K-3 III vs Pentax KP

Compared to Canon 90D

Nikon D3100
Canon 90D
  • $700
  • APS-C
  • Bigger pixels
  • Lighter weight
  • $1099
  • APS-C
  • Tilt-swivel screen
  • Shoot 4K video

Compare Nikon D3100 vs Canon 90D

Pentax K-3 III
Canon 90D
  • $1847
  • APS-C
  • Focus peaking
  • In-Camera Image Stabilization
  • $1099
  • APS-C
  • Less expensive
  • Tilt-swivel screen

Compare Pentax K-3 III vs Canon 90D

Compare Other Cameras?